The present invention relates to a system for protecting a main fluid circuit from an auxiliary fluid circuit should a leak develop in the auxiliary fluid circuit.
It is known to provide a fluid control system for earth-working machines including a main air circuit for operating components such as the service brake valves and the transmission cut-out valve and an auxiliary air circuit for operating components such as the parking valve, air horn, and other accessories. If a leak develops, for example, in the auxiliary air circuit and no pressure protection exists for the control system, the main air circuit can become inoperable since the two fluid circuits are integrated together. Since it is desirable that certain components, such as the service brakes, always have a supply of pressurized fluid available for their operation, there is a need for the fluid control system to at least include some means for protecting the fluid pressure in the main air circuit.
There have been pressure protection devices which offer a certain amount of protection, however, they do not permit the main fluid circuit to attain its peak operating pressure because they open at a pressure well below the maximum system pressure. These known devices cause the air compressor to run continuously as the system cycles between the opening and closing pressure settings. Thus, there has been a need for a system that protects the main fluid circuit from leaks in the auxiliary fluid circuit while permitting the main fluid circuit to maintain its peak operating pressure for maximum efficiency.